/**
 * Copyright (c) 2015-2018, Golly Hu 胡高 (3722711@qq.com).
 * <p>
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * <p>
 * http://www.apache.org/licenses/LICENSE-2.0
 * <p>
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package cn.hg.base.kit;

import java.io.IOException;
import java.lang.annotation.Annotation;
import java.util.HashSet;
import java.util.LinkedList;
import java.util.List;
import java.util.Set;

import org.springframework.core.io.Resource;
import org.springframework.core.io.support.PathMatchingResourcePatternResolver;
import org.springframework.core.io.support.ResourcePatternResolver;
import org.springframework.core.type.classreading.CachingMetadataReaderFactory;
import org.springframework.core.type.classreading.MetadataReader;
import org.springframework.core.type.classreading.MetadataReaderFactory;
import org.springframework.core.type.filter.AnnotationTypeFilter;
import org.springframework.core.type.filter.TypeFilter;
import org.springframework.util.ClassUtils;

/**
 * @author Golly
 */
public class ClassLoadKit {

	private static final String RESOURCE_PATTERN = "/**/*.class";
	private static ResourcePatternResolver resourcePatternResolver = new PathMatchingResourcePatternResolver();

	@SafeVarargs
	public static Set<Class<?>> getClassSet (String[] basePackages, Class<?> ancestorClass,
		Class<? extends Annotation>... annotationFilter) throws IOException, ClassNotFoundException {
		Set<Class<?>> classSet = new HashSet<>();
		List<TypeFilter> typeFilters = new LinkedList<>();

		if (annotationFilter != null) {

			for (Class<? extends Annotation> annotation : annotationFilter) {
				typeFilters.add(new AnnotationTypeFilter(annotation, false));
			}

		}

		for (String pkg : basePackages) {
			String pattern = ResourcePatternResolver.CLASSPATH_ALL_URL_PREFIX
				+ ClassUtils.convertClassNameToResourcePath(pkg) + ClassLoadKit.RESOURCE_PATTERN;
			Resource[] resources = ClassLoadKit.resourcePatternResolver.getResources(pattern);
			MetadataReaderFactory readerFactory =
				new CachingMetadataReaderFactory(ClassLoadKit.resourcePatternResolver);

			for (Resource resource : resources) {

				if (resource.isReadable()) {
					MetadataReader reader = readerFactory.getMetadataReader(resource);
					String className = reader.getClassMetadata().getClassName();

					if (ClassLoadKit.matchesEntityTypeFilter(reader, readerFactory, typeFilters)) {
						Class<?> clazz = Class.forName(className);

						if (ancestorClass != null && ancestorClass.isAssignableFrom(clazz) || ancestorClass == null) {
							classSet.add(clazz);
						}

					}

				}

			}

		}

		return classSet;
	}

	/**
	 * 检查当前扫描到的Bean含有任何一个指定的注解标记
	 *
	 * @param reader
	 * @param readerFactory
	 * @param typeFilters
	 *
	 * @return
	 *
	 * @throws IOException
	 */
	private static boolean matchesEntityTypeFilter (MetadataReader reader, MetadataReaderFactory readerFactory,
		List<TypeFilter> typeFilters) throws IOException {

		if (!typeFilters.isEmpty()) {

			for (TypeFilter filter : typeFilters) {

				if (filter.match(reader, readerFactory)) {
					return true;
				}

			}

			return false;
		}

		return true;
	}

}
